Subdivision using low pressure sewer mains with grinder pumps or Orenco systems

[Hawkeye66]

Does anyone have any experience with a subdivision that has a low pressure sewer system that relies on individual grinder pumps in the houses rather than a lift station?


We have a subdivision that was set up like this, and it was predicated on using Orenco treatment systems which discharge only gray water. Since that time we had two builders use grinder pumps and the developer now says these are ok. I have serious concerns about such a system generating sufficient pressure to push the flow up a 25’ incline over several hundred feet unless all the houses came on line at once. Let alone knowing if grinder pumps are acceptable. I put a moratorium on those and now all permits will go out with the specs for the Orenco System. The “mains” are only 2” and the stub lines are 1”. Doesn’t that almost force the discharge to be limited to water?

[estromberg]

Does anyone have any experience with a subdivision that has a low pressure sewer system that relies on individual grinder pumps in the houses rather than a lift station?


We have a subdivision that was set up like this, and it was predicated on using Orenco treatment systems which discharge only gray water. Since that time we had two builders use grinder pumps and the developer now says these are ok. I have serious concerns about such a system generating sufficient pressure to push the flow up a 25’ incline over several hundred feet unless all the houses came on line at once. Let alone knowing if grinder pumps are acceptable. I put a moratorium on those and now all permits will go out with the specs for the Orenco System. The “mains” are only 2” and the stub lines are 1”. Doesn’t that almost force the discharge to be limited to water?

Wouldn't the necessary HP needed in the pumps be smaller due to the size of the main? What I mean by that is this, if the mains are very small, a smaller pump can generate the necessary force to push the waste up the incline needed.

[Cardinal]

Wouldn't the necessary HP needed in the pumps be smaller due to the size of the main? What I mean by that is this, if the mains are very small, a smaller pump can generate the necessary force to push the waste up the incline needed.

Theoretically yes, but I am curious about the other question - solids. What about brown trout? And waste from the garbage disposal?

[Dan Staley]

Theoretically yes, but I am curious about the other question - solids. What about brown trout? And waste from the garbage disposal?

IIRC we had some of these in a few areas at one of my old places. I don't know what the homeowners did but our WWTP was able to handle the effluent. ISTM the homeowners had regular maintenance.

[mgk920]

Well, doesn't a grinder pump reduce whatever organic stuff that is sent to it into a fine slurry that will travel fairly easily? A small-diameter pipe then would ensure that pretty much everything will make it through to a larger gravity main with a minimum of clear water use.

Mike

[RPaul]

I'm a little confused... were or are there AdvanTex treatment units at the homes, are these STEP (Septic Tank Effluent Pump) to a centralized AdvanTex treatment works, or is this pumping to a muni system?

If grinder pumps are being used where the design called for a STEP, this will be VERY bad news, especially if there's an ATX downstream or if you're using on-site beds for final disposal.